Technical Field
Aspects of the present disclosure relate to a roller member having a cored bar and an elastic layer on an outer circumferential face of the cored bar, and an electrophotographic image forming apparatus, such as a copier, a printer, a facsimile machine, or a multifunction peripheral having at least two of the foregoing capabilities that includes the roller member, and particularly to a roller member, such as a secondary transfer roller or a secondary transfer opposite roller, to which high voltage is to be applied, and an image forming apparatus that includes the roller member.
Related Art
There has been conventionally known an image forming apparatus, such as a copier or a printer that uses a roller member in which an elastic layer is formed on the outer circumferential face of a cored bar, as a roller member such as a secondary transfer roller and a secondary transfer opposite roller, and performs a secondary transfer step by applying a secondary transfer bias being high voltage, to the roller member. Specifically, in a color image forming apparatus, an intermediate transfer belt travels in a predetermined direction, and respective toner images are primarily transferred onto the intermediate transfer belt and superimposed one on another at the positions of a plurality of primary transfer nips. Then, the toner image is secondarily transferred onto a recording medium conveyed to the position of a secondary transfer nip of the intermediate transfer belt and a secondary transfer roller. This secondary transfer nip is formed by the secondary transfer roller and a secondary transfer opposite roller contacting each other via the intermediate transfer belt. In addition, such a secondary transfer step is performed by applying a predetermined secondary transfer bias to at least either one of the secondary transfer roller and the secondary transfer opposite roller.
In some cases, a support including a collar or a spacer is rotatably installed on a support shaft of the roller member to which the secondary transfer bias is to be applied, so as not to generate leakage by applying the secondary transfer bias being high voltage, to the roller member such as the secondary transfer roller and the secondary transfer opposite roller.